Snake river physa snail
Encyclopedia
The snake river physa snail (Physella natricina) is a species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of a freshwater snail
Freshwater snail
A freshwater snail is one kind of freshwater mollusc, the other kind being freshwater clams and mussels, i.e. freshwater bivalves. Specifically a freshwater snail is a gastropod that lives in a watery non-marine habitat. The majority of freshwater gastropods have a shell, with very few exceptions....

, a gastropod in the family Physidae
Physidae
Physidae, common name bladder snails, are a monophyletic taxonomic family of small freshwater snails, aquatic pulmonate gastropod molluscs in the clade Hygrophila....

. It is endemic to Idaho
Idaho
Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....

 in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

.

The Snake River physa snail Haitia
Haitia
Haitia is a small genus of two species in the Loosestrife family of plants named for Haiti, the country where it was first collected. Both species are native to the island of Hispaniola....

(Physa
Physa
Physa is a genus of small, left-handed or sinistral, air-breathing freshwater snails, aquatic pulmonate gastropod mollusks in the family Physidae.These snails eat algae, diatoms and detritus.- Anatomy :...

) natricina Taylor, 1988 is a freshwater mollusc found in the middle Snake River
Snake River
The Snake is a major river of the greater Pacific Northwest in the United States. At long, it is the largest tributary of the Columbia River, the largest North American river that empties into the Pacific Ocean...

 of southern Idaho. It has an ovoid shell
Gastropod shell
The gastropod shell is a shell which is part of the body of a gastropod or snail, one kind of mollusc. The gastropod shell is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage...

 that is amber to brown in color, and has 3 to 3.5 whorls
Whorl (mollusc)
A whorl is a single, complete 360° revolution or turn in the spiral growth of a mollusc shell. A spiral configuration of the shell is found in of numerous gastropods, but it is also found in shelled cephalopods including Nautilus, Spirula and the large extinct subclass of cephalopods known as the...

. The physa can reach a maximum length of about 6.5 mm. The Snake River physa is believed to have evolved in the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....

-Holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...

 lakes and rivers of northern Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...

 and southeastern Idaho. The species may have existed in the Snake River for approximately 3.5 million years ago. While much information exists on the family Physidae
Physidae
Physidae, common name bladder snails, are a monophyletic taxonomic family of small freshwater snails, aquatic pulmonate gastropod molluscs in the clade Hygrophila....

, very little is known about the biology or ecology of this species. It is believed to be confined to the Snake River, inhabiting areas of swift current on the undersides of large cobbles and boulder-sized rocks. In 1995, the U.S. Fish and Wildlife Service reported the known modern range of the species to be from Grandview
Grandview
- Canada :* Grandview, Manitoba* Grandview, Thunder Bay, Ontario, a neighbourhood in Thunder Bay, Ontario* Grandview, Prince Edward Island, a small community in eastern Prince Edward Island- United States :*Grand View, Idaho*Grandview, Illinois...

, Idaho (ca. RM 487) to the Hagerman Reach of the Snake River (ca. RM 573). The Snake River physa is rare with fewer than 50 total individuals having been collected. The recovery area for the species extends from Snake River mile 553 to Snake River mile 675. It is currently listed as an Endangered species since 14 December 1992.
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